thistle

Cirsium steirolepis is a perennial or biennial thistle in the family Asteraceae, belonging to the large genus Cirsium, the true thistles. The genus Cirsium comprises over 200 species distributed across the Northern Hemisphere, with major diversity in Europe, Asia, and North America. The epithet 'steirolepis' derives from Greek meaning 'sterile-scaled' or 'rigid-scaled,' likely referring to distinctive phyllary characteristics—the scale-like involucre bracts that enclose the capitulum. Like all true thistles, Cirsium steirolepis produces leaves with spiny-toothed or deeply lobed margins bearing sharp spine tips, stems that may be winged with decurrent leaf bases, and discoid capitula with numerous purple, pink, or white tubular florets. The involucre is densely covered with spiny-tipped phyllaries in multiple imbricate rows. The pappus consists of feathery (plumose) bristles arranged in several rows, which is diagnostic for Cirsium and distinguishes it from related genera such as Carduus. Achenes are oblong with an elaiosome attachment point attractive to ants. Thistles are ecologically valuable as nectar sources for bumblebees, butterflies, and specialized long-tongued flies, as well as seed sources for goldfinches and other seed-eating birds. The geographic range of Cirsium steirolepis likely spans Europe or Asia, where it occupies meadows, pastures, roadsides, and disturbed habitats. Thistles are generally tolerant of grazing pressure owing to their spiny defenses and ability to resprout from deep taproots.